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Manuscript Title: MEAMfit: A reference-free modified embedded atom method (RF-MEAM) energy and force-fitting code
Authors: Andrew Ian Duff
Program title: MEAMfit
Catalogue identifier: AEWY_v1_1
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 203(2016)354
Programming language: Fortran.
Computer: Linux based workstations.
Operating system: Linux.
RAM: 120 Megabytes
Keywords: Interatomic potential, Fitting, Lattice-vibrations.
PACS: 07.05.Tp.
Classification: 16.1.

External routines: TOMS611 Unconstrained Minimization [1] included in the MEAMfit code.

Does the new version supersede the previous version?: Yes

Nature of problem:
Fitting embedded atom method (EAM) and reference-free modified embedded atom method (RF-MEAM) potentials [2-3] to energies and forces produced by VASP [4-7].

Solution method:
A computer program is presented which uses a conjugate-gradient minimizer paired with a genetic algorithm to fit EAM and RF-MEAM potentials to energies and/or atomic forces read directly from VASP output files. Potentials produced by the code are directly usable with the LAMMPS [8] or Camelion [9] molecular-dynamics packages.

Reasons for new version:
Bugs fixed; improvements made.

Summary of revisions:
Various bug fixes; speed of single-shot energy and force calculations (not optimization) increased by x10; elements up to Cn (Z=112) now correctly read from vasprun.xml files; EAM fits now produce Camelion output files; changed max number of vasprun.xml files to 10,000 (an unnecessary lower limit of 10 was allowed in the previous version).

Additional comments:
User manual provided.

Running time:
The run-time depends on the required level of accuracy of the final potential. For an EAM potential fit to 670 energies, a few hours on a single core is usually sufficient to produce a potential with R = 12%-13% (see Equation. 9 in main-text for definition). To ensure a maximally optimized potential however (R = 12%), a run-time of 24 hours is recommended. To optimize a RF- MEAM potential, a further 24 hours should be allowed. One will already find an improvement over the EAM using just a single core, however to ensure a maximally optimized potential, one should run several instances of MEAMfit in parallel.

References:
[1] J. E. Dennis, D. Gay and R. E. Welsch, ACM Trans. on Math. Soft., 7 (1981) 348-368.
[2] M. I. Baskes, Materials Science and Engineering A, 261 (1999), 165.
[3] M. Timonova and B. J. Thijsse, Modelling Simul. Mater. Sci. Eng., 19 (2011) 015003
[4] G. Kresse, J. Hafner, Phys. Rev. B 47 (1993) 558.
[5] G. Kresse, J. Hafner, Phys. Rev. B 49 (1994) 14251.
[6] G. Kresse, J. Furthmüller, Comput. Mat. Sci. 6 (1996) 15.
[7] G. Kresse, J. Furthmüller, Phys. Rev. B 54 (1996) 11169.
[8] S. Plimpton, J. Comp. Phys. 117 (1995)
[9] http://tinyurl.com/camelion11-53